[lldb] Add an extra optional did_read_live_memory to Target::ReadMemory

Target::ReadMemory may or may not read live memory, but whether it did
read from live memory or from the filecache is opaque to callers. Add an
extra out parameter to indicate whether live memory was read or not.

Author: augusto2112

lldb/include/lldb/Target/Target.h

@@ -1193,11 +1193,14 @@ class Target : public std::enable_shared_from_this<Target>,
   // 2 - if there is a process, then read from memory
   // 3 - if there is no process, then read from the file cache
   //
+  // The optional did_read_live_memory parameter will be set true if live memory
+  // was read successfully.
+  //
   // The method is virtual for mocking in the unit tests.
   virtual size_t ReadMemory(const Address &addr, void *dst, size_t dst_len,
                             Status &error, bool force_live_memory = false,
-                            lldb::addr_t *load_addr_ptr = nullptr);
-
+                            lldb::addr_t *load_addr_ptr = nullptr,
+                            bool *did_read_live_memory = nullptr);
   size_t ReadCStringFromMemory(const Address &addr, std::string &out_str,
                                Status &error, bool force_live_memory = false);
 

lldb/source/Target/Target.cpp

@@ -1921,7 +1921,8 @@ size_t Target::ReadMemoryFromFileCache(const Address &addr, void *dst,
 
 size_t Target::ReadMemory(const Address &addr, void *dst, size_t dst_len,
                           Status &error, bool force_live_memory,
-                          lldb::addr_t *load_addr_ptr) {
+                          lldb::addr_t *load_addr_ptr,
+                          bool *did_read_live_memory) {
   error.Clear();
 
   Address fixed_addr = addr;
@@ -2020,6 +2021,8 @@ size_t Target::ReadMemory(const Address &addr, void *dst, size_t dst_len,
       if (bytes_read) {
         if (load_addr_ptr)
           *load_addr_ptr = load_addr;
+        if (did_read_live_memory)
+          *did_read_live_memory = true;
         return bytes_read;
       }
     }

lldb/unittests/Expression/DWARFExpressionTest.cpp

@@ -111,7 +111,8 @@ class MockTarget : public Target {
 
   size_t ReadMemory(const Address &addr, void *dst, size_t dst_len,
                     Status &error, bool force_live_memory = false,
-                    lldb::addr_t *load_addr_ptr = nullptr) /*override*/ {
+                    lldb::addr_t *load_addr_ptr = nullptr,
+                    bool *did_read_live_memory = nullptr) /*override*/ {
     auto expected_memory = this->ReadMemory(addr.GetOffset(), dst_len);
     if (!expected_memory) {
       llvm::consumeError(expected_memory.takeError());